Or introducing a hazard to your home or work place! Writes Robert Tulloch who, as an Engineering Officer with TCA’s electrical safety laboratory, has seen some highs and lows in products entering the market over the past 15 years.

Bargain stores, discount stores and markets are selling cheap power tools but are you aware that some of these tools may not have been tested to the Australian Standard for electrical safety?

Over the past 15 years of testing, some similarities have emerged between cheap European power tools and some Asian manufactured imported tools. Most of the problems have occurred in the areas of insufficient insulation, low quality thermoplastic enclosure and the use of non-approved components.

To attain the required degree of protection from electrical shock, most power tools employ double insulation (Two layers of insulation, basic and supplementary or a single, reinforced layer of insulation equivalent to two layers of insulation). Supplementary and reinforced insulation have minimum thickness requirements of 1.0 mm and 2.0 mm respectively and are also checked for adequacy by high voltage testing.

There is no specific thickness requirement for basic insulation, which has to be tested for compliance by high voltage testing. It is the area of basic insulation on armatures and field windings where some problems have arisen. High voltage testing failures lower than 100 Volts have occurred (Minimum high voltage withstand required: 1250 Volts)

Another area of concern is that the enclosures are being manufactured with low quality thermoplastics that do not withstand the normal environment in which the power tool is to be used. As a result, fatigue fractures and distortion of the enclosure may occur.

Voids in the extrusion process of the enclosures are also a concern as these can retain moisture therefore bridging the supplementary insulation of the enclosure.

Another area is the flexible cord guard entry, which is a point of common breakdown and hazard to the user, the cord guards are manufactured from excessively rigid materials that do not allow the cord to flex over a sufficient length therefore shortening the cord life
The flexible cords themselves have been seen not to comply with an International or Australian Standard and may be found to crack, split or become non-flexible.

When purchasing any power tool look for reputable and well known brands, look for Australian Approval marking, for example Nxxxxx or similar on both the power tool, flexible cord and plug.

Buy a power tool large enough and properly dimensioned for the work you intend to carry out. The retailer can generally advise you.

Also, when purchasing any power tool make sure it contains the C-Tick marking to show compliance with electromagnetic emissions. For battery operated power tools, the charger will have to be both safety approved and marked with the C-Tick.

Check the tools regularly for cracks in the enclosure or damaged power cords. Should that happen, have them serviced by authorised persons.

Power tool armature with minimal insulation between the winding and the core
(Basic Insulation broke down at less than 100V during high voltage test)